To lift an object which otherwise rests on the ground and is spaced apart therefrom by a narrow gap, a thin jack is required. Referring to FIG. 1 through FIG. 3, there are shown schematic views of a conventional thin jack 1. The thin jack 1 consists of a hydraulic hole 2, a hydraulic chamber 3, and a support post 4. Oil is introduced into the hydraulic chamber 3 through the hydraulic hole 2 to elevate the support post 4, thereby lifting an object 1000.
Referring to FIG. 3, after lifting the object 1000, users put at least a support 5 in the vicinity of the thin jack 1 to support the object 1000, drain the oil from the hydraulic chamber 3 to lower the support post 4 back to its initial level shown in FIG. 1, and eventually remove the thin jack 1 from below the object 1000.
As indicated above, the support post 4 will not descend to thereby allow the thin jack 1 to be removed from below the object 1000, unless the oil is drained from the hydraulic chamber 3. However, it takes time to drain the oil from the hydraulic chamber 3.
In addition, the thin jack 1 is not capable of lifting the object 1000 by a distance larger than the longest possible distance traveled by the support post 4 of the thin jack 1.
Furthermore, to raise the thin jack by means of a plurality of underpinning block (not shown) with a view to solving the problem described in the preceding paragraph, the users have to move the thin jack 1 repeatedly. However, conventional thin jacks are not lightweight enough to be moved repeatedly but easily by average users.
Accordingly, it is imperative to provide a thin jack which is not only capable of controlling elevation of a support post of the thin jack while lifting an object, but also allow users to raise the thin jack continuously and easily without moving the thin jack horizontally.